Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

1

ADC/MCA Module With PC Interface(RS232/RS485/USB/Ethernet)

Georgi Georgiev, Ivaylo Peev

Institute For Nuclear Research And Nuclear Energy

Bulgarian Academy Of Sciences

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

2

The Goal

• Building a combination of fast ADC with low differential non-linearity (DNL) and multi-channel analyzer.

• Compact size.

• Operate multiple ADC/MCA modules by one computer.

• Remote operation and management over TCP/IP.

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

3

The Solution

• Using Gatti correction proposed by C. Cottini, E.Gatti and V.Svelto in 1963.

• Involving modern technology.

– Fast A/D and D/A converters.

– Programmable logic devices.

– “Smart” approach.

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

4

Implementation

ADC with S/HADC/MCA

Control

Logic

&

RAM

FPGAPrecise DAC

Input

stagesInput

Processor

PC Interface

(USB/Ethernet)

Peak

Detector

Pile Up

Gate

Electronic

Control DAC

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

5

Main Points

• Precise peak detector used for accurate start of measurement process.

• Fixed dead time differential input ADC with S/H.

• Only one precise voltage reference source is used in order to minimize possible errors.

• Predefined spectra capture time (Live time).

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

6

Main Points

• High precision DAC used to shift the measurement point on each event.

• 4-channel DAC used to control LLD, ULD and other parameters.

• Fully buffered spectra capture and transfer.

• Micro-controller manages the communication channel and handles the protocol.

• Optically isolated interface (RS232/485/USB).

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

7

The device

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

8

Features and performance

• Total processing time of 640ns.

• No added dead time for pulses with 125ns shaping time.

• 1k, 2k and 4k channel spectra captured.

• Digital control of LLD, ULD and other front-end parameters.

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

9

Software

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

10

0

1000

2000

3000

4000

5000

6000

7000

Sample results25.19 KeV

8.04 KeV

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

11

Possible signal sources

• SDD detectors.

• NaI(Tl) scintillators.

• Conventional detectors.

Georgi Georgiev, Ivaylo Peev - Bulgarian Academy Of Sciences

12

Applications

• Fast on-line analysis.

• Analysis using high intensity sources.